在相同工艺条件下生产了高碳（碳质量分数达到0.157%，高碳系）和低碳并添加铌、钼元素（Nb-Mo系）的2种成分780 MPa级双相钢，对比研究了2种钢的显微组织、拉伸性能、扩孔性能，以及软硬相的纳米压痕硬度。结果表明：2种钢的显微组织均为铁素体和马氏体；与高碳系试验钢相比，Nb-Mo系试验钢的铁素体晶粒得到细化，屈服强度和屈强比提升，并具有更高的扩孔率；高碳系试验钢中的马氏体因碳含量较高而硬度较大，且硬度分布更发散，Nb-Mo系试验钢中马氏体的硬度分布较集中；Nb-Mo系试验钢中铁素体和马氏体两相的纳米压痕硬度差更小，因此扩孔性能更优。

780 MPa dual phase steels with two kinds of composition were produced under the same manufacturing condition; one had high carbon conent (carbon mass fraction of 0.157%, high-C series), and the other had low carbon content and was added with Nb and Mo elements (Nb-Mo series). The microstructure, tensile properties, hole expansion performance and nanoindentation hardness of hard and soft phases of the two steels were studied and compared. The results show that the microstructures of the two steels consisted of ferrite and martensite. Compared with those of the high-C series test steel, the ferrite grains of the Nb-Mo series test steel were refined, the yield strength and yield ratio were improved, and the hole expansion rate was higher. Due to the higher carbon content, the martensite in the high-C series test steel had relatively high hardness, and the hardness distribution was ralatively divergent. The hardness distribution of the martensite in the Nb-Mo series test steel was concentrated. The nanoindentation hardness difference between the ferrite and the martensite in the Nb-Mo series test steel was smaller, so the hole expansion performance was better.